JP3723988B2 - Differential pressure booster - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a differential pressure booster that boosts and outputs an operating force exerted on an input rod using a differential pressure between a constant pressure chamber and a variable pressure chamber.
[0002]
[Prior art]
Conventionally, in a differential pressure booster, a reaction disk such as rubber is provided at the tip of an input rod to which a pedaling force from a brake pedal is input, and an output rod for transmitting a pedaling force to a master cylinder is provided following the reaction disk. . Further, the power piston disposed in the housing so as to be slidable in the axial direction and the movable wall moving integrally with the power piston divide the internal space formed by the housing into a constant pressure chamber and a variable pressure chamber. The operation of such a differential pressure booster is achieved by separating the variable pressure chamber from the constant pressure chamber by the operation of the control valve by the advance of the input rod and communicating with the high pressure source, and the advance of the power piston by the differential pressure between the constant pressure chamber and the variable pressure chamber. Then, the output rod is pressed through the reaction disk, and the pedal force is transmitted to the output rod by the determination of the boost ratio by the reaction disk by pressing the reaction disk directly on the input rod.
[0003]
For example, in the technology disclosed in Japanese Patent Publication No. 3-24383, the reaction disk for determining the boost ratio is disposed on the inner disk on the disk and outside the inner disk with a gap between the output disk and the output shaft. And an outer disk having a ring-shaped receding contact surface. In the reaction disk having this configuration, the contact area with the output rod is small when the input rod is lightly operated, and the contact area with the output rod is large when the input rod is strong. For this reason, with a light operating force, the boost ratio is low due to the contact of only the inner disk disc, and even if the brake pedal is depressed lightly, the brake does not work excessively, facilitating fine adjustment of the braking force and improving the brake feeling. On the other hand, with a strong operating force, the entire reaction disk can come into contact with the output rod due to the compression deformation of the inner disk, and a specified boost ratio can be obtained, thereby improving the effectiveness of the brake.
[0004]
[Problems to be solved by the invention]
The reaction disk is molded by pouring molten rubber into the mold, and the dimensions of the reaction disk, such as the outer diameter and thickness, change when the change in the boost ratio or boost ratio is changed. And a new mold is required to mold it. Since the reaction disk of the above prior art is composed of an inner disk and an outer disk, a mold satisfying this shape and the dimensions of each part is required, resulting in a significant cost increase. Further, in order to change the boost ratio and the change point of the boost ratio, the dimensions of each part of the reaction disk must be changed, and a new mold must be manufactured, which is expensive.
[0005]
The present invention can change the boost ratio between when the operating force of the input rod is weak and when it is strong, and can further change the boost ratio and the change point of the boost ratio at low cost. Is a technical issue.
[0006]
[Means for Solving the Problems]
In order to solve the above technical problem, the technical means taken in the invention of claim 1 is provided with an annular groove provided at least near the outer periphery of the axial contact surface of the output rod with the reaction disk.
[0008]
[Action]
The operation of the invention of claim 1 will be described. When the light operating force is applied to the input rod, the reaction disk contacts the surface of the output rod in the axial contact surface other than the annular groove. When this is done, the reaction disk contacts the entire axial contact surface of the output rod, so that a high boost ratio is obtained. On the other hand, by arbitrarily setting the width and depth of the annular groove, it is possible to freely change the boost ratio and the change point of the boost ratio, and the annular groove is connected to the reaction disk of the output rod. By providing at least the vicinity of the outer periphery of the axial contact surface, it is easy to cut the axial contact surface with the reaction disk of the output rod, and the change in the boost ratio and boost ratio at low cost. Will be able to change.
[0010]
【Example】
An embodiment according to the present invention will be described with reference to the drawings.
[0011]
FIG. 1 is a sectional view of a first embodiment in which the present invention is applied to a negative pressure type booster, and FIG. 2 is an enlarged sectional view around a reaction disk. In the figure, the housing 10 includes a first shell 13, a second shell 12, and a third shell 11. The housing 10 is obtained by fitting the second shell 12 and the first shell 13 in an airtight manner inside the third shell 11.
[0012]
A sealed space Rb is formed between the first shell 13 and the second shell 12.
[0013]
A movable wall 15 is fixed in the space Rb. The interior of the space Rb is further divided by a movable wall 15 into a constant pressure chamber Rb1 and a variable pressure chamber Rb2. The movable wall 15 includes a metal power piston 151, an annular plate 152, and a diaphragm 153. The inner peripheral portion of the annular plate 152 is engaged with the outer peripheral portion of the power piston 151. The inner peripheral portion 153a of the diaphragm is supported on the outer periphery of the power piston 151, and is also sandwiched between the inner peripheral portions of the holding member 154 and the annular plate pressure 152. The outer peripheral portion 153b is the first shell 13 and the third shell. 11 is airtightly held.
[0014]
Communication passages 151 a and 151 b are formed inside the power piston 151. The communication path 151a connects the constant pressure chamber Ra2 and the constant pressure chamber Rb2. The communication path 151b connects the variable pressure chamber Ra1 and the variable pressure chamber Rb1.
[0015]
A plurality of bolts 21 are fixed to the first shell 13 and are attached to a dashboard (not shown) by the bolts 21.
[0016]
The third shell 11 is formed with a recess 111 for fixing a master cylinder (not shown). A seal 35 that seals between the third shell 11 and the output rod 43 is loosely inserted into the recess 111. The seal 35 is fixed by inserting a master cylinder, and is further provided with a groove portion 35a for air release.
[0017]
The second shell 12 is caulked and fixed inside the first shell 13 to form a sealed space Ra between the third shell 11 and the second shell 12. A movable wall 14 is fixed in the space Ra. The interior of the space Ra is further divided by the movable wall 14 into a constant pressure chamber Ra1 and a variable pressure chamber Ra2. The movable wall 14 includes an annular plate 142 and a diaphragm 143. One end of the annular plate 142 is supported by the step portion 151 c of the power piston 151. The outer peripheral end portion 143a of the diaphragm 143 is airtightly held between the second shell 12 and the third shell 11, and the inner peripheral end portion 143b is a cut portion and holding portions 151c and 151d of the power piston 151, and the annular plate 142. It is held by the inner peripheral part.
[0018]
A reinforcing plate 16 is fixed inside the third shell 11. A plurality of bolts 22 for fixing the master cylinder are fixed to the reinforcing plate 16.
[0019]
The third shell 11 is connected to a connector 17 that communicates the space Ra2 with a negative pressure source (not shown) such as an internal combustion engine.
[0020]
An annular seal member 31 fixed to the second shell 12 is provided between the second shell 12 and the power piston 151. An annular seal member 32 fixed to the first shell 13 is provided between the first shell 13 and the power piston 151. The power piston 151 is supported by the seal members 31 and 32 and can slide in the axial direction of the housing 10.
[0021]
An air cleaner 51, an input rod 41, an air valve 42, and an output rod 43 are inserted into the power piston 151. An air valve 42 is slidably inserted into the power piston 151 while its movement is restricted by the key 151e. A ball joint portion 411 is formed at one end of the input rod 41. The ball joint portion 411 is inserted into the first air valve 421 and fixed by caulking. The input rod 41 is slidably supported by the first air valve 421. The air valve 42 includes a first air valve 421 that supports the input rod 41 and a second air valve 422 that has one end in contact with the first air valve 421.
[0022]
A control valve is configured between the input rod 41 and the air valve 42. The control valve includes a control valve 61 urged toward the air valve 42 by a spring 60, a power piston 151, and a first air valve 421. The end of the control valve 61 is held between the power piston 151 and the holding member 52. The holding member 52 is in contact with one end of a spring 53 that urges the spring 60 and the input rod 41 toward the initial position. The other end side of the spring 53 abuts on the flange portion 412 of the input rod, and further holds the air cleaner 51 with an extra winding portion wound a plurality of times on the outer peripheral side.
[0023]
A cup portion 431 is formed at one end of the metal output rod 43, and a reaction disk 432 is inserted into the cup portion 431. An annular groove 431a is provided on the outer periphery of the bottom surface of the cup portion 431 (the axial contact surface with the reaction disk 432). Further, the output rod 43 is slidably supported by the seal member 35 of the recess 111 of the third shell 11.
[0024]
A main spring 45 is provided between the cup portion 431 and the third shell 11, and the main spring 45 presses the power piston 151 toward the inoperative position.
[0025]
Next, the operation of this embodiment will be described.
[0026]
When an operation force forward (leftward in FIG. 1) is applied to the input rod 41 by depressing a brake pedal (not shown), the movable wall 14 is moved by the pressure increase in the variable pressure chambers Ra1 and Rb1 caused by the well-known operation of the control valve. 15 is pushed forward, and the power piston 151 is pushed. Pushing forward of the power piston 151 is transmitted to the output rod 43 via the reaction disk 432. On the other hand, the reaction disk 432 is elastically deformed by the pressing force of the power piston 151 and presses the second air valve 422 to generate a reaction force on the input rod 41.
[0027]
FIG. 3 is a diagram showing the relationship between the operating force (input) to the brake pedal and the output from the output rod 43. In the figure, points a to b show known jumping characteristics, and show the reaction disk 432 until it elastically deforms and contacts the second air valve 422. Points b to c indicate the reaction disk 432 is further elastically deformed and is filled in the annular groove 431a. Points c to d indicate the time from when the reaction disk 432 is filled in the annular groove 431a until the assisting force of the booster disappears. Note that after the input exceeds the point d, the operating force applied to the input rod 41 is output to the output rod 43 as it is.
[0028]
As can be seen from FIG. 3, in the region from point c to point d, the boost ratio is larger than in the region from point b to point c, and the braking effectiveness is increased. As a result, when a light operating force is applied to the input rod 41, the reaction disc 432 comes into contact with a surface other than the annular groove 431a of the axial contact surface of the output rod 43, so that a low boost ratio is obtained and a strong operating force is obtained. Is applied, the reaction disk 432 contacts the entire axial contact surface of the output rod 43, so that a high boost ratio is obtained.
[0033]
【The invention's effect】
The effect of the invention of claim 1 will be described. When the light operating force is applied to the input rod, the reaction disk contacts the surface of the output rod in the axial contact surface other than the annular groove. When this is done, the reaction disk contacts the entire axial contact surface of the output rod, so that a high boost ratio is obtained. On the other hand, by arbitrarily setting the width and depth of the annular groove, it is possible to freely change the boost ratio and the change point of the boost ratio, and the annular groove is connected to the reaction disk of the output rod. By providing at least the vicinity of the outer periphery of the axial contact surface, it is easy to cut the axial contact surface with the reaction disk of the output rod, and the change in the boost ratio and boost ratio at low cost. Will be able to change.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a negative pressure booster according to a first embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view around the reaction disk of FIG.
FIG. 3 is a diagram illustrating a relationship between an input and an output of the negative pressure booster according to the first embodiment.
FIG. 4 is a sectional view of a negative pressure booster according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Housing 14, 15 ... Movable wall 41 ... Input rod 42 ... Air valve 43 ... Output rod 151 ... Power piston 151f ... Reaction case (2nd Example)
151g ... annular groove (second embodiment)
432 ... Reaction disk 431 ... Output rod cup 431a ... Annular groove (first embodiment)
Ra1, Rb1 ... Transformer chamber Ra2, Rb2 ... Constant pressure chamber

Claims (1)

A housing, a constant pressure chamber located in the housing and constantly maintaining a constant pressure in the housing, and a variable pressure chamber selectively communicating with the constant pressure chamber or at least a high pressure source higher than the constant pressure chamber Power piston, an air valve that slides in the axial direction of the power piston and the axial direction of the power piston, and a control valve that is capable of contacting the power piston and the air valve and is always urged in the direction of contacting both A control valve that selectively communicates the variable pressure chamber with the high pressure source or the constant pressure chamber, an input rod connected to the air valve for operating the control valve, and the constant pressure The propulsive force generated in the power piston due to the pressure difference between the chamber and the variable pressure chamber is transmitted from the power piston to the output rod and the air bar. In differential pressure booster and a reaction disc applying reaction force to the blanking,
A differential pressure booster comprising an annular groove provided at least near the outer periphery of an axial contact surface of the output rod with the reaction disk.

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